Connective tissue dysfunction is emerging as a potentially important, and so far mostly overlooked, factor in the pathophysiology of chronic low back pain (LBP). We have developed and tested a novel instrument (StromaGlide) and test (Connective Tissue Motion Measure - CTMM) -quantifying the functional behavior of perimuscular connective tissues. The results of preliminary data strongly suggest that CTMM is reduced in chronic LBP. In this project, we plan to further test the performance of the CTMM as a biomarker in cross sectional and longitudinal studies of humans with and without LBP. We will also improve the commercial viability of the project by upgrading device components with less expensive (but equally well performing) FDA compliant subcomponents. Aim 1: Comparison of CTMM (test) in LBP vs No-LBP: We will follow up on the results of Phase 1 with a fully powered comparison of CTMM across 144 subjects, 72 with LBP and 72 with No-LBP. LBP and No-LBP groups will be frequency-matched for age, sex and BMI. In each subject, CTMM will be measured once bilaterally in the back. Based on our preliminary results, we hypothesize that CTMM will be reduced on average in the LBP group. Aim 2: Within-subject correlation of short term repeated CTMM: We will assess the stability of CTMM over repeated short term measurements. All LBP and No-LBP subjects tested in Aim 1 (N=144) will be re-tested one hour and one day following the initial test. We hypothesize that the CTMM will be reliable with an intra class correlation (ICC) greater than 0.8. Aim 3: Relationship of CTMM to clinical measures: All LBP subjects tested in Aim 1 (N=72) will also be evaluated with established measures of LBP symptoms and impairment. We hypothesize that CTMM will negatively correlate with the numeric pain index, McGill pain score, Oswestry disability index and functional measure score (50 foot walk, repeated sit-to-stand and repeated forward bend). All LBP subjects tested in Aim 1 (N=72) will also be retested 9 months and 15 months later along with repeated assessment of symptoms and impairment (target n=60; 20% attrition allowance). We hypothesize that CTMM will be a significant time-varying covariate in predicting temporal changes in the functional and disability tests. Aim 4: Upgrade StromaGlide components to decrease manufacturing costs and adopt an FDA compliant design: We will substitute principal subsystems with low-cost, custom designed FDA compliant components suitable for commercialization. This will not alter device performance, rather it will reduce estimated manufacturing costs of these subsystems significantly. Upgraded device performance will be verified to match existing specifications.